Certain Cisco IOS releases in 12.2S based trains with maintenance release number 25 and later, 12.3T based trains, and 12.4 based trains reuse a Tcl Shell process across login sessions of different local users on the same terminal if the first user does not use tclquit before exiting, which may cause subsequent local users to execute unintended commands or bypass AAA command authorization checks, aka Bug ID CSCef77770.